4 barrel carb questions

Just parking a 400 cfm carburetor on a stock engine will produce nothing but drivability issues, and lower fuel mileage.

In order to get any benefit from that much increase in carburation one needs to install oversized valves, increase compression, re-curve distributor, increase size of exhaust system, and probably change to a more performance orientated cam shaft.

You have to think of an engine as an air pump, and how much air can it move. No matter how big one makes the opening to the engine, unless the rest of the pump is enlarged it still can only move the same amount of air before the enlarged carburetor was installed.

Check out what Josh has to say about carburetors on the other /6 site:
http://slantsix.org/articles/Josh_Carb_Article.htm